B.2.10—Enhanced greenhouse effect
- Syllabus
- First assessment 2025
- Objective
- —
- Level
- HL
Distinguish the Enhanced Greenhouse Effect
Natural greenhouse effect
The natural greenhouse effect is the normal warming produced when atmospheric gases absorb and re-emit some of Earth’s outgoing infrared radiation. It helps keep Earth’s surface suitable for life.
Enhanced greenhouse effect
The enhanced greenhouse effect is the augmentation of that effect due to human activity. Increased concentrations of greenhouse gases can increase absorption and downward re-radiation of infrared energy.
Primary cause in the syllabus
Burning fossil fuels is identified as a primary cause because it increases atmospheric carbon dioxide and contributes to changes in the Earth–atmosphere energy balance. Other human activities can affect greenhouse-gas concentrations too.
Common trap
Do not say that the greenhouse effect itself is caused only by humans. Human activity enhances a naturally occurring effect.
B.2.10 Exam Analysis
Assessment in practice
1 marksHow it is assessed
The evidence repeats a multiple-choice question asking for a primary cause of the enhanced greenhouse effect.
Command terms
State / Identify
What earns marks
Define enhanced greenhouse effect as the human-caused augmentation of the natural greenhouse effect. When identifying a cause, the evidence expects burning fossil fuels; connect it to increased greenhouse-gas concentration rather than simply naming a temperature rise.
Watch for
Saying the natural greenhouse effect is human-caused, or selecting melting ice rather than a cause that changes greenhouse-gas concentration.
Representative question
Question 1
[Maximum number: 1]
What is a primary cause of the enhanced greenhouse effect?
A
Melting of ice at Earth's poles
B
Increases in volcanic activity
C
Deforestation of rainforests
D
Burning of fossil fuels
D